Self-closing thermal protection sheath and its method of fabrication

ABSTRACT

A self-closing thermal protection sheath ( 13 ) includes an interleaved structure comprising firstly a monofilament ( 10 ) and secondly strips ( 11 ) of metallized foil.  
     Application in particular to protecting wiring harnesses or fluid pipes of an automobile vehicle.

[0001] The present invention relates to a self-closing thermalprotection sheath.

[0002] It also relates to a method of fabricating a self-closing thermalprotection sheath.

[0003] Generally speaking, the present invention relates to self-closingsheaths used in automobile vehicles to provide mechanical protection forwiring harnesses or fluid pipes in the vehicle.

[0004] Sheaths that self-close around wiring harnesses or pipes toprovide mechanical and thermal protection thereof are known in the art.

[0005] Thus wiring can be protected from infrared radiation by sheathshaving a reflective structure.

[0006] In particular, woven sheaths in the form of a flat tape to whichan aluminized layer is then fixed are known in the art. The sheath isthen closed around a wiring harness and held in place by Velcro™ and/oradhesives.

[0007] Glass fiber and/or polyester woven tapes that are thermoformed toa tubular shape are also known in the art. An aluminized foil can beprovided on the external surface of the self-closing tubular sheath.

[0008] Thus the sheath can be fitted and automatically closed around awiring harness. Closure adhesives then keep it closed, especially atbends, where the self-closing sheath tends to open.

[0009] An object of the present invention is to propose an improvedself-closing thermal protection sheath.

[0010] To this end, it provides a self-closing sheath, that includes aninterleaved structure comprising firstly a monofilament and secondlystrips of metallized foil.

[0011] This yields a unique structure that has the special feature of areflective surface able to protect wiring from infrared radiation.

[0012] Furthermore, this structure with no attached aluminized foil isflexible so the sheath can be conformed better when fitted to elongatemembers, especially at bends.

[0013] According to a preferred feature of the invention, the sheath hasa woven structure comprising a monofilament as the weft filament andstrips of metallized foil as warp filaments.

[0014] This structure can be produced by a conventional loom, themonofilament conferring stiffness on the flexible sheath.

[0015] The strips of metallized foil preferably consist of a polyesterfilm aluminized on both sides.

[0016] Thus the strips can be obtained by cutting them out from apolyester film.

[0017] According to another aspect of the invention, a method offabricating the above kind of self-closing sheath includes the followingsteps:

[0018] producing an interleaved structure in the form of a flat tapecomprising firstly a monofilament and secondly strips of metallizedfoil, and

[0019] thermoforming said flat tape into a tubular self-closing sheath.

[0020] The interleaved structure can therefore be made flat and thenthermoformed into a split tubular sheath so that it can be fitted aroundelongate members simply by spreading apart the edges of the sheath andthen closing the sheath up around the members concerned.

[0021] Other features and advantages of the invention will become moreapparent in the course of the following description.

[0022] In the appended drawings, which are provided by way ofnonlimiting example only:

[0023]FIG. 1 is a view of a portion of a sheath according to theinvention before thermoforming, and

[0024]FIG. 2 is a partial perspective view of a self-closing sheathaccording to the invention.

[0025] One embodiment of a self-closing thermal protection sheathaccording to the invention is described first with reference to FIGS. 1and 2.

[0026] The thermal protection sheath has an interleaved structurecomprising a monofilament 10 and strips of metallized foil 11.

[0027] The interleaved structure is woven in the conventional way with aweft thread and warp threads.

[0028] Of course, other interleaved structures could be used, inparticular a knitted or braided structure, and possibly produceddirectly in a tubular form.

[0029] The weft filament of the woven structure is a monofilament.

[0030] The monofilament can be a polyester filament with a diameter from0.1 mm to 0.5 mm.

[0031] This kind of polyester monofilament can withstand hightemperatures, of the order of 150° C., and impart some strength to theself-closing sheath.

[0032] The warp filaments of the woven structure are strips ofmetallized foil.

[0033] The metallized foil strips are preferably strips of polyesterfilm aluminized on both sides.

[0034] Thus aluminized polyester films available off the shelf can becut into strips. The strips can be formed into a spool ready forsubsequent use on a loom.

[0035] It will be noted that it is beneficial if the aluminized foildoes not incorporate any varnish that could absorb some of the infraredradiation and thereby reduce the reflective power of the thermalprotection sheath.

[0036] The strips of metallized foil are preferably from 2 mm to 5 mmwide.

[0037] Generally speaking, the strips could be from 1 mm to 15 mm wide.

[0038] The Applicant has fabricated sheaths with strips 3 mm wide,producing an entirely satisfactory woven structure.

[0039] The woven tape further includes a selvage filament 14 parallel tothe strips 11 of metallized foil.

[0040] The selvage filament is woven with the strips and thereforeextends along a longitudinal edge of the sheath.

[0041] The selvage filament limits fraying of the sheath. It may bebeneficial to use a colored filament as the selvage filament, firstly sothat its presence can easily be detected (its absence constitutes adefect) and secondly so that the “bound” edge of the fabric can easilybe identified.

[0042] As shown clearly in FIG. 2, the self-closing sheath thus assumesa tubular shape having an overlapping portion S subtending an angle from45° to 180°.

[0043] In this example the overlapping portion subtends an angle ofsubstantially 180°.

[0044] This relatively wide overlapping portion means that the thermalprotection sheath can be fitted to wiring harnesses and pipes withdifferent diameters with guaranteed closure of the sheath by overlappingof the edges.

[0045] Thus a reflective structure is obtained from the strips ofaluminized foil, requiring no addition of an attached aluminum foil.

[0046] This one-piece structure yields a flexible sheath that can befitted to wiring harnesses and pipes of diverse shapes.

[0047] A method of fabricating the above kind of self-closing sheath isdescribed next.

[0048] In practice, an interleaved structure is produced first, forexample a woven structure, in the form of a flat tape 12 as shown inFIG. 1, for example.

[0049] Thus a conventional loom can be used to weave a flat tape from amonofilament and strips of metallized foil.

[0050] The flat tape is then thermoformed into a self-closing tubularsheath 13 shown in FIG. 2.

[0051] The step of weaving the flat tape uses as the weft filament amonofilament, for example a polyester monofilament, and as warpfilaments strips of metallized foil made from an aluminized polyesterfilm.

[0052] The thermoforming step preferably includes the followingsubsteps:

[0053] cold forming the flat tape into a tubular shape, with anoverlapping area subtending an angle of less than or equal to 180°.

[0054] Thus the tape can be cold-formed around a former of appropriateshape so that an overlapping area is produced.

[0055] heating the cold-formed tubular shape;

[0056] The heating temperature is between the temperature at which thepolyester softens and the temperature at which it melts. This heatingstep is of relatively short duration, generally one minute or less.

[0057] cooling the thermoformed sheath.

[0058] The heated sheath is then cooled rapidly, generally by contactwith the surrounding air.

[0059] Thanks to the softening and cooling of the polyester filament,the sheath treated as above remains closed, with an overlapping portion.

[0060] Of course, many modifications can be made to the embodimentdescribed above without departing from the scope of the invention.

[0061] In particular, the self-closing thermal protection sheath couldbe produced by a different fabrication method, for example with abraided or knitted structure.

[0062] The interleaved structure could be produced directly in a tubularform, requiring no thermoforming of the resulting tape.

[0063] Furthermore, the woven structure could include a selvage filamenton each longitudinal edge of the sheath.

[0064] Finally, the interleaved structure could include two layers,namely a first layer comprising the strips of metallized foilinterleaved with a monofilament, adapted to reflect infrared radiation,and a second layer, for example a layer of glass fibers, adapted toinsulate the wiring or pipes from heat transmitted by convection orconduction.

[0065] The interleaved structure could be obtained by a double-sidedweaving method, the side with the glass fibers constituting the interiorface of the tubular sheath.

1. A self-closing thermal protection sheath, characterized in that itincludes an interleaved structure comprising firstly a monofilament (10)and secondly strips (11) of metallized foil.
 2. A self-closing sheathaccording to claim 1, characterized in that it has a woven structurecomprising a monofilament (10) as the weft filament and strips (11) ofmetallized foil as warp filaments.
 3. A self-closing sheath according toeither claim 1 or claim 2, characterized in that the strips (11) ofmetallized foil consist of a polyester film aluminized on both sides. 4.A self-closing sheath according to any of claims 1 to 3, characterizedin that the strips (11) of metallized foil are from 2 mm to 5 mm wide.5. A self-closing sheath according to any of claims 1 to 4,characterized in that the monofilament (10) is a polyester filament witha diameter from 0.1 mm to 0.5 mm.
 6. A self-closing sheath according toany of claims 1 to 5, characterized in that it comprises an overlappingportion (5) subtending an angle from 45° to 180°.
 7. A method offabricating a self-closing sheath according to any of claims 1 to 6,characterized in that it includes at least one selvage filament (14)parallel to the strips (11) of metallized foil and extending along alongitudinal edge of said sheath.
 8. A method of fabricating aself-closing sheath according to any of claims 1 to 7, characterized inthat it includes the following steps: producing an interleaved structurein the form of a flat tape (12) comprising firstly a monofilament (10)and secondly strips (11) of metallized foil, and thermoforming said flattape (12) into a tubular self-closing sheath (13).
 9. A fabricationmethod according to claim 8, characterized in that it includes a step ofweaving a flat tape (12) comprising a monofilament (10) as weft filamentand strips (11) of metallized foil as warp filaments.